Light table with multiple axis tilting, and tension control of traveling illuminated media

ABSTRACT

The invention concerns a light table having capability for adjustable tilting in multiple modes and to extreme angularity relative to horizontal, and with further provision for rapid reversal of film travel at any speed without loss of film tension, both hand and motor operation being enabled.

United States Patent Stewart et a1.

[ 1 Aug. 1, 1972 [54] LIGHT TABLE WITH MULTIPLE AXIS TILTING, AND TENSION CONTROL OF TRAVELING ILLUMINATED MEDIA [72] Inventors: Wilton A. Stewart, Pacific Palisades; Ying-Nien Yu, Marina Del Rey,

both of Calif.

[73] Assignee: Integraphic Inc., Santa Monica,

Calif.

[22] Filed: Sept. 3, 1969 21 Appl. No.: 854,980

[52] US. Cl ..242/67.4, 40/86 R, 108/23, 242/ [51] Int. Cl. ..Bh 17/02, A47b 37/00 [58] Field of Search..242/67.l R, 67.1 D, 67.5, 67.2, 242/55, 67.3; 108/23, 90, 53; 40/53 R, 86 R, e 86 A, A, 31 R; 26/70 [56] References Cited UNITED STATES PATENTS 2,595,055 4/1952 Clark et a1. ..242/67.4 3,002,703 10/1961 Hinchman ..242/ 3,203,636 8/1965 Owen ..242/75.5l X 3,358,393 12/1967 Lewis ..40/31 3,364,604 I/ 1968 Donaldson et a1 ..40/31 Primary ExaminerGeorge F. Mautz Attorney-White & Haefliger [5 7] ABSTRACT The invention concerns a light table having capability for adjustable tilting in multiple modes and to extreme angularity relative to horizontal, and with further provision for rapid reversal of film travel at any speed without loss of film tension, both hand and motor operation being enabled.

5 Claims, 19 Drawing Figures PATENTEDAus 1 1912 SHEEI 1 U? 5 7 I N vewraes.

PATENTEUAUS 1 I972 SHEET 5 BF 5 LIGHT TABLE WITH MULTIPLE AXIS TILTING, AND TENSION CONTROL OF TRAVELING ILLUMINATED MEDIA BACKGROUND OF THE INVENTION This invention relates generally to light tables or boxes, and, more particularly concerns a highly versatile light table embodying a number of unusual advantages having to do with table tilting in multiple modes, and film or sheet drive control.

In the past, light tables have lacked certain important advantages which characterize the present invention. Among them are capability for adjustable tilting of the light table in multiple modes and to extreme angularity with respect to horizontal; film transport means which provides for rapid reversal of film travel at any speed and eliminates loss of tension during such reversal; and a high degree of simplicity and compactness of overall construction of the table; and the combination of hand operation and motor operation within one system which eliminates the need of dual systems existent in the conventional light table film transport.

SUMMARY OF THE INVENTION It is a major object of the invention to provide a light table embodying combinations and sub-combinations of advantages as referred to above, whereby problems with prior tables are effectively eliminated. Basically and as respects the table tilt feature of the invention, an assemblyis provided which comprises: a table having a top plate which is translucent to pass light therethrough for illuminating the underside of media overlying the plate; a first hinging support for the table defining a first axis about which the table may be adjustably tilted; a second hinging support for the table defining a second axis about which the table may be adjustably tilted; and control means operatively connected with the table to control tilting thereof about each of the axes independently of tilting about the other of the axes. Typically, the table may be sufficiently free of the second support when supported by the first support and tilted about the first axis that tilting of the table about the second axis is prevented, and vice versa. Further,

an adjustable connection may be provided to cooperate with one of the supports to selectively control pivoting of the table about the two axes. As a result, the table may be selectively tilted in either of two modes, as for example endwise and frontward, by operation of a single actuator as will be seen.

In this regard, the actuator structure may, with unusual advantage, include a rotatable lead screw and an arm, one end of which is movable lengthwise of the screw in response to screw rotation, and the other end of the arm may extend proximate the underside of the table in supporting relation therewith throughout tilting of the table in both modes in response to lead screw rotation. Further, releasable means may be provided to be operable to selectively connect the table to either of the supports for controlling selective tilting of the table about the two axes, as will be described. Finally, means may typically be carried by the table to effect controllable travel of a sheet or film across the translucent plate, in either of the tilt modes.

As respects film or sheet transport, the invention typ ically embodies a pair of spools spaced apart relative to the translucent plate for winding and unwinding the sheet, thereby to displace it endwise over the plate; a pair of electrical motors each connected in driving relation with one of the spools, and control means operable in one mode to effect motor current supply to cause one motor to rotate one spool in sheet winding sense and the other motor to retard rotation of the other spool in sheet unwinding sense, and in another mode to effect motor current supply to cause the other motor to rotate the other spool in sheet winding sense and the other to retardv rotation of the one spool in sheet unwinding sense. As a result sheet tension is maintained during transport. In this regard, the spools may typically be releasably mounted to the table to rotate about spool axes, and the table and mounted spools may be tiltable as a unit, as referred to above.

Additional features include provision for mounting the spools for adjustment shifting parallel to the spool axes so that the motors may be coupled to spools of different lengths; and the provision of control means that includes a variac or equivalent, a transformer, switches through which different transformer windings may be coupled to the motors, a manual control to operate the variac, and a cam operated by the manual control to selectively operate the switches, with advantages as will appear.

These and other objects and advantages of the invention, as well as the details of an illustrative embodiment will be made clear from the following detailed specification and drawings in which:

DRAWING DESCRIPTION FIG. 1 is a perspective showing of one form of the invention;

FIG. 2 is an enlarged front elevation taken in section to show how endwise table tilt may be effected;

FIG. 3 is a top plan view, partly in section, taken on line 33 of FIG. 2;

FIG. 4 is an end elevation taken on line 4-4 of FIG.

FIG. 5 is an end elevation like FIG. 4, but showing adjustment shifting of a motor drive for one of the sheet or film spools;

FIG. 6 is a section taken on lines 6-6 of FIG. 3;

FIG. 7 is a section taken on lines 77 of FIG. 3;

FIG. 8 is an enlarged section taken on line 88 of FIG. 2 to show one table pivot support;

FIG. 9 is a view like FIG. 8, but showing the table rotated about an axis through the pivot support;

FIG. 10 is a view of the FIG. 8 pivot support with the table displaced upwardly relative to the support during table pivoting about another axis;

FIG. 11 is a section taken on line 1 1-11 of FIG. 8;

FIG. 12 is a section taken on line 1212 of FIG. 3;

FIG. 13 is a section taken on line 13--13 of FIG. 3;

FIG. 14 is a fragmentary section taken on line 14- 14 of FIG. 3;

FIG. 15 is a fragmentary section taken on line 15- 15 of FIG. 3;

FIG. 16 is an enlarged fragmentary section taken on line 16-16 of FIG. 5; and

FIGS. 17a-17c are wiring diagrams showing electrical motor control.

DESCRIPTION OF PREFERRED EMBODIMENT In the drawings a light box or table is carried by first and second hinging supports 11 and 12 on a mounting cabinet 13. In this regard, the table typically contains a light source and has a top plate 14 which is longitudinally elongated and translucent to pass light upwardly for illuminating the underside of media overlying the plate. Such media may comprise a film or sheet 15 adapted to be drawn longitudinally over the plate.

In the example shown, the table also includes top, bottom and upright side and end panels 16, 17, 18 and 19, with flanges 20 and 21 projecting downwardly from the bottom panel for table supporting engagement with the hinging support 11, as seen in FIG. 12. Further, a flange 22 projects downwardly from the bottom panel 17 for table supporting engagement with the hinging support 12.

Support 11 may typically and advantageously comprise a lateral tube 23 defining a first axis 24, whereas support 12 may typically and advantageously comprise a longitudinal rod 25 defining a second axis 26 which is generally normal to axis 24. Rod 25 is shown as attached to and carried by the cabinet 13 at structure 10- cations 27 and 28; whereas tube 23 is carried at one end by L-shaped bracket 29 so as to pivot about axis 26 when the table is subjected to forward tilting, i.e., from the table position (flat) represented in FIG. 7 to the table position (tilted) represented in broken lines 10a in FIG. 6. L-shaped bracket 29 has one arm 29a attached to one end of tube 23, and another arm 29b pivotally carried by the end of rod 25 projecting beyond cabinet structure 28, as best seen in FIG. 3.

Accordingly, the table 10 may be tilted frontwardly, as described, or alternatively about lateral axis 24 as represented by the table tilted position indicated by broken lines 106 in FIG. 2. In the latter mode, the flange 22 is elevated relative to the rod 25, as for example is represented in FIG. 10. Note that the flange carries a C-shaped section 30 of a bearing sized to seat downwardly on and rotate relatively about the rod 25 to accommodate forward tilting of the table, as is clear from FIGS. 8 and 9. Under these circumstances, the table is rotated about the second axis defined by rod 26, and the tube 23 is rotated with the table. On the other hand, when the table is tilted about axis 24 as indicated at 100 in FIG. 2, the table is free of the second support 12 including rod 25 so that pivoting about the latter is prevented until such time as the table is returned to horizontal position so that section 30 may engage rod 25.

It is an important feature of the invention that an adjustable connection is provided to cooperate with one of the two hinging supports to selectively control pivoting of the table about the two axes 24 and 26, with the result that the tilt mode of the table may be very simply controlled. One such adjustable connection is shown in FIGS. 3 and 12 to include a latch plunger 34 controlled by a knob 35, and having a terminal 340 adapted to penetrate a keeper opening 36. A compression spring 37 within tube 23 urges the plunger flange 38 to the right in FIG. 12, maintaining penetration of the plunger terminal 340 into the keeper opening, which is defined by structure 39 integral with the cabinet. In this condition, the rod 34 is coaxial with the tube 23 and axis 24 is maintained to extend laterally and horizontally so that the table may be pivoted as at 100 in FIG. 2, the flanges 20 and 21 pivoting about the tube 23 (which extends through flange bores 20a and 21a).

When it is desired to pivot the table about longitudinal axis 26, the plunger knob 35 is retracted to the left, to position 35a in FIG. 12, whereby the terminal 34a is released from the opening. If desired, the plunger may be held in retracted position by a suitable detent. During each forward pivoting, the tube 23 rotates or tilts with the table due to its connection therewith as via flanges 20 and 21.

The above described adjustable connection may be considered as one aspect of a control means operatively connected with the table to control tilting thereof about each of the axes 24 and 26. Another aspect of such control means includes actuator structure movable to effect table tilting about such axes, and a single manual control for effecting movement of the actuator structure.

As one example of such actuator structure, FIGS. 2 and three illustrate the provision of a rotatable lead screw 40, and an arm 41 one end of which is movable lengthwise of the screw in response to screw rotation, and the other end of which extends proximate the underside of the table in supporting relation therewith throughout tilting of the table about axes 24 and 26. In this regard, the lead screw may be bearing supported at 42 and 43; a manual control shaft 44 may be rotatable by handle 45 and disc 46 to cause helical gear 47 on shaft 44 to rotate the lead screw as by rotating gear 48 on the screw; and a follower 49 on the screw may be advanced and retracted along the screw to advance and retract the lower end of the actuator arm 41. The upper end of the arm has ball joint connection at 49a to the lower panel 17 of the table. These components, and especially the arm 41, may advantageously be so located that when the plunger 34 is latched in FIG. 12 position, turning of the screw 40 by the handle 45 will necessarily result in table pivoting in the mode seen at 10c in FIG. 2; whereas, when the plunger 34 is released from FIG. 12 latched condition, turning of screw 40 by handle 45 will necessarily result in table pivoting in the mode seen at 10a in FIG. 6. As a result, only one manual control is needed to effect table pivoting in two different modes, as for example up to from horizontal in each mode.

A further important aspect of the invention concerns the provision for transport of media such as a sheet or film back and forth over the illumination plate on the tiltable table in its various tilt modes and without loss of sheet tension. In this regard, two spools 50 and 51 are provided to wind and unwind the sheet 15, thereby to displace it endwise over the plate 14. The spools are mounted to the table at opposite ends thereof, for rotation about axes 52 and 53. Spool end flanges such as are indicated at 54 and 55 confine the wound sheet there between, the flanges being carried by drums 56 defining end openings 57 to receive penetration of support shafts 58 seen in FIG. 14. The latter shafts, which are keyed to the spools at 59, turn in support bearings 60 and 61 which are carried by tube and plate structures 62 and 63, the latter being attached to the table 10 as is clear from FIGS. 1 and 3. Manually rotatable knobs 64 are integral with the shafts 58 so that the spools may be slowly turned, manually, to slowly displace a sheet or film over the plate 14, when the drive motors are not energized.

The opposite ends of the spools are coupled to drive structure including electrical motors 66, such drive structure including motor shafts connected to drive pulleys 67, V-belts 68, driven pulleys '88, and driven shafts 69 releasably connected to the spools. These drive elements are mounted to carriages 70, each including a pair of plates 70a and 70b. Each carriage is in turn slidably mounted by sleeves 71 and 72 on parallel bars 73 and 74 which extend laterally between front plate 63 and rear plate 75 affixed to the table. Accordingly, each carriage may be adjustably shifted lengthwise of bars 73 and 74 to connect the drive structureto a particular spool inserted into position onto a support shaft. Also, spools of different length, corresponding to different sheet or film widths, may thereby be accommodated. Note the provision, in FIGS. 5 and 16, of a set screw 76 threaded into sleeve 71 to engage bar 73, and having a knob 77, which may be tightened to clamp the carriage to the bar when the drive is coupled to the spool. It is clear from FIG; 4 that the entire drive structure as described is adapted to pivot with the light table.

FIGS. 1, 3 and 13 show the provision of sheet guide rollers 80 and 81 proximate each spool. Such upper and lower rollers guide the sheet onto the table as it unwinds off a spool proximate one end of the table, and guide the sheet as it leaves the opposite end of the table and winds onto the spool proximate that end; The rollers are carried by shafts 82 and 83, which are supported by plates 63 and 75, previously referred to. Upper shafts 82 are hinged at 84, so as to be pivotable upwardly as seen in FIG. 13, allowing insertion or withdrawal of the sheet 15 in the spool 86 between the guide rollers. Pivoted clips 87 seen in FIG. I retain the projecting ends of the upper shafts in lowered position during sheet transport between the spools.

FIGS. 17a, 17b and 17c show the wiring diagram providing electrical motor control. AC Power is connected to the center terminal 100 and one end terminal 101, of the variable output voltage transformer T The output voltage varies from zero when terminal 102 is coincident with terminal 100 to full AC Power line voltage when terminal 102 is coincident with terminal 101 or to negative full AC Power line voltage when terminal 102 is coincident with terminal 103. The output voltage on terminal 102 of T is connected to the normally open, N. 0. terminals of both switches S and S Transformer T provides a motor current supply to motors M and/or M to retard rotation of the respective spools in a sheet winding sense when switch S and/or switch S are not actuated by the cam 104. For convenience and to provide a single control, the cam and terminal 102 of T are mounted so as to move together. The output voltage on terminal 102 of T is applied to a winding of motor M through switch S, when the cam is rotated to actuate switch S Alternatively, the output voltage on terminal 102 of T is applied to a winding of motor M through switch 5;. when the cam is rotated to actuate switch 8:.

When both switches S, and S are not actuated by the cam, as in FIG. 17a, the retarding torques of motors M and M are equal and opposite, and the media (sheet or film) is stationary under tension and not transported in either direction.

When the cam is manually or otherwise rotated to actuate switch S but not switch S and the terminal 102 on transformer T is manually or otherwise positioned between terminals and 101 to provide a desired output voltage as in FIG. 17b, current is supplied to motor M and AC Power through switch S2 to rotate one spool in a sheet winding sense. At the same time, current is supplied to motor M from transformer T through switch S to retard rotation of the other spool in a sheet unwinding sense. Thus said sheet is wound onto the spool driven by motor M and tension is maintained in the sheet by retardation of the other spool by motor M Alternatively, the sheet may be wound onto the spool driven by motor M by rotating the cam to actuate switch S1 and positioning terminal 102 of transformer T between terminals 103 and 101 of transformer T At the same time, current is supplied to motor M from transformer T through switch S to retard rotation of the spool driven by motor M Thus said sheet is wound onto the spool driven by motor M and tension is maintained in the sheet by retardation of the other spool by motor M The speed and the direction of winding the-sheet onto one or the other spool is controlled by adjusting the location of terminal 102 between terminals 103 and 101 on transformer T and selection of the appropriate spool for retardation is controlled by the cam actuating switches S and S Thus smooth and continuous control of the sheet winding speed is obtained from full speed in one direction to zero to full speed in the other direction while continually maintaining retardation tension on the sheet to prevent inertial effects in slowing down to throw slack in the film.

The arrangement of the electrical connections to transformer T produce an important circuit simplification. AC electrical power is connected to terminals 100 and 101- and is also applied, through phasing capacitor C to one winding to motor M Power of the opposite phase is generated across terminals 103 and 100 of transformer T which, when applied to one winding of motor M, will produce a rotation of the armature of motor M in a direction opposite to that of motor M Thus a transformer with a single center-tapped winding can be used to produce opposite rotations of two motors.

A:- further simplification of the electrical circuit is shown in FIG. to eliminate transformer T by connecting the second winding of motor M to a fixed tap, 105, on transformer '1 between terminals 103 and 100 and by connecting the second winding of motor M to a fixed tap, 106, on transformer T between terminals 100 and 101.

We claim:

1. In a light table assembly, the combination comprising a. a table having a top plate which is translucent to pass light therethrough to illuminate the underside of a sheet overlying the plate,

b. a pair of spools spaced apart relative to the plate for winding and unwinding a sheet thereby to displace the sheet endwise of and over the plate,

c. a pair of electrical motors and drive means connecting each motor in driving relation with one of said spools, therebeing structure carrying the drive means at opposite ends of the table for relative shifting into and out of driving relation with the spools, and

(1. control means operable in one mode to effect motor current supply to cause one motor to rotate one spool in sheet winding sense and the other motor to retard rotation of the other spool in sheet unwinding sense, and in another mode to effect motor current supply to cause said other motor to rotate said other spool in sheet winding sense and said one motor to retard rotation of said one spool in sheet unwinding sense.

2. The combination of claim 1 including support means releasably mounting said spools to said table for rotation about spool axes, the table and spools being tiltable as a unit.

3. The combination of claim 2 wherein the motors are shiftable with the drive means on said structure and parallel to said spool axes whereby the motors may be coupled to spools of different lengths.

4. The combination of claim 1 wherein said control means includes a variac, a transformer, switches through which different transformer windings may be coupled to the motors a manual control to operate the variac, and a cam operated by said manual control to selectively operate said switches.

5. The combination of claim 3 including manually rotatable control knobs coupled to said spools for transmitting rotary drive to the spools independently of said motors. 

1. In a light table assembly, the combination comprising a. a table having a top plate which is translucent to pass light therethrough to illuminate the underside of a sheet overlying the plate, b. a pair of spools spaced apart relative to the plate for winding and unwinding a sheet thereby to displace the sheet endwise of and over the plate, c. a pair of electrical motors and drive means connecting each motor in driving relation with one of said spools, therebeing structure carrying the drive means at opposite ends of the table for relative shifting into and out of driving relation with the spools, and d. control means operable in one mode to effect motor current supply to cause one motor to rotate one spool in sheet winding sense and the other motor to retard rotation of the other spool in sheet unwinding sense, and in another mode to effect motor current supply to cause said other motor to rotate said other spool in sheet winding sense and said one motor to retard rotation of said one spool in sheet unwinding sense.
 2. The combination of claim 1 including support means releasably mounting said spools to said table for rotation about spool axes, the table and spools being tiltable as a unit.
 3. The combination of claim 2 wherein the motors are shiftable with the drive means on said structure and parallel to said spool axes whereby the motors may be coupled to spools of different lengths.
 4. The combination of claim 1 wherein said control means includes a variac, a transformer, switches through which different transformer windings may be coupled to the motors a manual control to operate the variac, and a cam operated by said manual control to selectively operate said switches.
 5. The combination of claim 3 including manually rotatable control knobs coupled to said spools for transmitting rotary drive to the spools independently of said motors. 